Medical Examination of Diving Fatalities Proceedings Summary | DAN and UHMS Medical Examination of Diving Fatalities Symposium Introduction The DAN/UHMS sponsored Medical Examination of geared towards medical examiners, many of the issues Diving Fatalities Symposium was held on June 18, 2014 discussed in the workshop are pertinent to dive in St. Louis, Missouri. Although the symposium was professionals.
Why it may not be drowning n A large number of deaths in scuba ascribed to include inhalation of inert gas (nitrogen), air hose drowning are in fact due to other causes: specifically, entanglement (entrapment), and cuttlefish attack that sudden cardiac death (SCD), and to a lesser extent, caused perforated tympanic membrane, leading to arterial gas embolism (AGE). panic, rapid ascent and gas embolism; there were also other causes labeled drowning. n Some cases which have been labeled as “immersion” or “drowning” have subsequently been found to be n Most medical examiners would call it drowning, due to other causes. Some of the more unusual causes simply because someone was in the water.
2 Proceedings Summary | Medical Examination Of Diving Fatalities Cardiac conditions are common causes n Sudden cardiac death (SCD): two most common n Left ventricular hypertrophy (LVH): atherosclerotic causes of SCD sudden causes in adults are coronary disease often co-exists with another risk factor for artery disease and left ventricle hypertrophy (LVH). SCD and that is LVH. If you don’t recognize it, you are missing a huge risk factor for sudden death. n Atherosclerotic heart disease: it is not the heart attack that kills the person instantly, heart attacks and n LVH may play a significant role in SCD in divers subsequent damage to the myocardium kill people due to the stress on the body from diving may over a time course of hours to days. It is the precipitate arrhythmias and death. dysrhythmia that kills people instantly. n If we know what risk factors to look for, we may be n You can’t see an arrhythmia on autopsy. able to improve our fitness to dive screenings and potentially prevent some of these deaths.
Looking for preventable causes of death n Fatality investigation: in most cases investigation n Injury research depends on the quality of data pro usually ends with establishing proximal cause of vided by investigation. Legal investigation may death. Unintentional or natural cause of death provide answers on questions of how it happened but investigation usually stops short of pursuing root often not concerned with “why”. The medical causes. examination may answer what were the cause of death and the mode of death.
Field investigation - preserving the evidence
Three general patterns to a diver’s death:
n First, death occurs underwater with no rescue or resuscitation attempted. Disadvantage by possible delay in between when the diver dies and is recovered – autopsy info can be altered or affected.
n Second, diver has a triggered even in the water and is brought to shore or boat for attempted rescue but dies prior to transportation to medical facility. Usually provides a witness to describe what happened.
n Third, diver is transported to a medical facility and survives for a few hours or days. Advantages are that imaging and lab tests may guide determination of the cause of death, however autopsy findings may be altered by the survival interval and medical intervention.
Diving conditions and diving equipment may cause or contribute to a diver’s death. Information may be lost as witnesses leave, forget equipment, or worse, equipment is returned to the family.
Field investigation is categorized into 6 parts:
n History n Antemortem events n The environment n Body recovery n Medical care administered before death n Body and equipment recovery and documentation and preservation of evidence
3 Proceedings Summary | Medical Examination Of Diving Fatalities Post mortem, how to n Very few forensic pathologists have significant medical and surgical history, recent health status, and experience with the investigation of fatalities any medications taken on a regular basis and on the involving divers who were breathing compressed gas. day of the mishap need to be known. n Fewer than 100 combined deaths occurring in n Cardiovascular disease in particular is a frequent the US, Canada, and the Caribbean each year. factor in a diving related fatality, especially in older divers. n Pathologists should be aware of the circumstances surrounding the fatal dive mishap, but the diver’s past What medical examiners need to know about rebreathers n Three main root causes of fatal accidents with rebreathers: - Diver error (the most common) - Mechanical problems - Electronic problems n An autopsy cannot reveal hypoxia, hyperoxia, or hypercapnia (the three most common causes of rebreather fatalities). In most cases, the medical examiner cannot detect the root cause of a rebreather fatality.
Expert panel review of investigation and autopsy findings n Guidelines identified by common trends seen - Ensure that your skill level and familiarity are in diver death: appropriate for conditions.
- Ensure physical fitness to dive: train for your sport - Have your equipment serviced and maintained regularly. and be sure that you exercise regularly and follow a healthy diet. - Account for all divers (a physical, individual response should be received from every diver before entering/after - Use the buddy system. exiting.
- Follow your training: check your gauges often, - Avoid overhead environments unless properly trained respect depth and time restrictions, and do not dive and equipped. beyond your training limits. - Breath-hold divers should remember to use the buddy - Weight yourself properly and remember to release system and be aware of the dangers of shallow-water your weights when appropriate. blackout.
SOURCE: Denoble PJ (editor). Medical Examination of Diving Fatalities Symposium Proceedings. Durham, NC, Divers Alert Network, 2015, 64 pp.
4 Proceedings Summary | Medical Examination Of Diving Fatalities Appendix F in the Recreational Diving Fatalities Workshop Proceedings is the Autopsy Protocol for Recreational Diving Fatalities by Dr. James Caruso In: Vann RD, Lang MA, eds. Recreational Diving Fatalities. Proceedings of the Divers Alert Network 2010 April 8-10 Workshop. Durham, NC: Divers Alert Network, 2011. IBSN#978-0615-54812-8.
History This is absolutely the most important part of the Not only will the last dive or dive series be invaluable to evaluation of a recreational diving fatality. Ideally, one the investigation, much can be learned about the diver should obtain significant past medical history with a by looking at previous dives made, including frequency, special focus on cardiovascular disease, seizure disorder, depth, ascent habits and with certain computers even diabetes, asthma and chronic obstructive pulmonary breathing gas usage. Written dive logs are also a valuable disease. Medications taken on a regular basis as well as on source of information related to the diver’s experience the day of the dive should be recorded, and information level and dive habits. regarding how the diver felt prior to the dive should be obtained. Any history of drug or alcohol use must also be Questions include: noted. n When did the diver begin to have a problem The dive history is extremely important. If possible, the (predive, descent, bottom, ascent, postdive)? investigator should find out the diver’s experience and certification level. The most important part of the history n Did the diver ascend rapidly (a factor in air embolism will be the specific events related to the dive itself. The and pulmonary barotrauma)? dive profile (depth, bottom time) is an essential piece of information, and if the diver was not diving alone, n Was there a history of entrapment, entanglement eyewitness accounts will be invaluable. With the or trauma? near-universal use of dive computers, the computer used by the deceased diver should be interrogated, and if it has n If resuscitation was attempted, what was done, and a download function all recent dives should be reviewed. how did the diver respond?
5 Proceedings Summary | Medical Examination Of Diving Fatalities External examination and preparation
A thorough external examination including heart and great vessels have been examined under water documentation of signs of trauma or animal bites or for the presence of gas, the water may be evacuated and envenomation should be carried out. Palpate the area a standard autopsy may be performed. between the clavicles and the angles of the jaw for evidence of subcutaneous emphysema. X-rays of the head, Carefully examine the lungs for bullae, emphysematous neck, thorax and abdomen should be taken to look for blebs and hemorrhage. free air. Postmortem CT imaging can be obtained as an alternative. Note any interatrial or interventricular septal defects. Carefully check for evidence of cardiovascular disease and Modify the initial incision over the chest to make a “tent” any changes that would compromise cardiac function. or “pocket” out of the soft tissue (an “I” shaped incision) and fill this area with water. A large bore needle can be Toxicology: Obtain blood, urine, vitreous, bile, liver and inserted into the second intercostal spaces on each side; if stomach contents. Not all specimens need to be run, but desired, any escaping air can be captured in an inverted, at least look for drugs or abuse. If an electrolyte water-filled, graduated cylinder for measurement and abnormality is suspected or if the decedent is a diabetic, analysis. As the breast-plate is removed, note any gas the vitreous fluid may prove useful for analysis. escaping from vessels. An alternative test for pneumothorax consists of teasing through the intercostal Prior to opening the skull, tie off all the vessels in the neck muscles with a scalpel and observing the relationship to prevent artifactual air from entering the intracranial between the visceral and parietal pleura as each pleural vessels. Tie the vessels at the base of the brain once the cavity is entered. If the two pleural layers are still adjacent skull is opened. Disregard bubbles in the superficial veins until the pleural cavity is breached, there is no evidence of or venous sinuses. Examine the meningeal vessels and the a pneumothorax. If a pneumothorax had occurred during superficial cortical vessels for the presence of gas. Carefully the final dive, the lung would already be at least partially examine the Circle of Willis and middle cerebral arteries deflated and not up against the parietal pleura. for bubbles.
The pericardial sac can be filled with water and the Have an expert evaluate the dive gear. Are the cylinders chambers of the heart may be incised with a scalpel to empty? If not, the gas should be analyzed for purity look for any intracardiac gas. As was possible for the (a little carbon monoxide goes a long way at depth). pleural cavities, escaping gas may be captured and All gear should be in good working order with analyzed, but most medical examiner offices do not have accurate functioning gauges. the resources for such endeavors. After the mediastinum,
6 Proceedings Summary | Medical Examination Of Diving Fatalities Possible findings Air embolism Drowning Intra-arterial and intra-arteriolar air bubbles in the brain While drowning essentially remains a diagnosis of and meningeal vessels, petechial hemorrhages in gray and exclusion, there are some anatomic findings that are white matter, evidence of COPD or pulmonary observed with considerable frequency. The lungs usually barotrauma (pneumothorax, pneumomediastinum, appear hyperinflated and can even meet at the midline subcutaneous emphysema), signs of acute right heart when the anterior chest wall is removed. Lungs are failure, pneumopericardium, air in coronary and retinal typically heavy and edematous, and pleural effusions may arteries. be present. A moderate amount of water and even some plant material may be present, not only in the airway but Decompression sickness also in the esophagus and stomach. Dilatation of the right Lesions in the white matter in the middle third of the ventricle of the heart is commonly observed as is spinal cord including stasis infarction, if there is a patent engorgement of the large central veins. Fluid is also foramen ovale (or other potential right to left heart shunt) often found in the sphenoid sinus. a paradoxical air embolism can occur due to significant venous bubbles entering the arterial circulation. Venomous stings or bites A bite or sting on any part of the body, unexplained Carbon monoxide poisoning edema on any part of the body, evidence of anaphylaxis Deaths due to carbon monoxide poisoning are rare in or other severe allergic reaction. recreational diving, but they do occur. Autopsy findings are similar to carbon-monoxide-related deaths in other settings, with the classic finding of a cherry red color to the organs and blood. A carboxy-hemoglobin measurement should be obtained as routine toxicology in all diving- related deaths to exclude the contribution of contaminated breathing gas.
Interpretation The presence of gas in any organ or vessel observed at the Gas present only in the left ventricle or if analysis shows autopsy of someone who breathed compressed gas just the gas in the left ventricle has a higher oxygen content prior to death is not conclusive evidence of decompression than that present on the right side would also be sickness or air embolism. During a dive, especially one of supportive for the occurrence of an air embolism. considerable depth or bottom time, inert gas dissolves in the tissues, and the gas will come out of solution when Intravascular gas from decomposition or off-gassing from the body returns to atmospheric pressure. This, combined the dive would contain little oxygen and be made up of with postmortem gas production, will produce bubbles mostly nitrogen and carbon dioxide. in tissue and vessels. The phenomenon has caused many experienced pathologists to erroneously conclude that Deeper, longer dives can cause decompression sickness a death occurred due to decompression sickness or air and significant intravascular (mostly venous) gas. embolism. Decompression sickness is rarely fatal and more commonly causes significant morbidity (illness and Intravascular bubbles present predominantly in arteries injury) in severe cases. Rapid ascents and pulmonary and observed during an autopsy performed soon after the barotrauma are associated with air embolism. death occurred is suspicious for air embolism. The dive history will help support or refute this theory.
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